Provably Fair Verifier
Paste the values from a site's fairness panel and this tool re-runs the cryptography: it checks that SHA-256(server seed) matches the hash the site published before you bet, then derives HMAC-SHA256(server seed, client seed:nonce) and the common game outcomes. Everything runs locally in your browser via WebCrypto, no value you enter is sent anywhere.
What this proves, and what it doesn't
A matching commitment proves the site didn't swap its seed after seeing your bets; matching outcomes prove each roll followed deterministically from the seeds. Two limits to keep in mind. First, the HMAC step is near-universal, but the mapping from digest to game result varies by site, compare against the formula on the site's fairness page, and treat the derivations here (roulette % 15, percent % 10001 / 100, bustabit-style crash) as the common defaults. Second, a fair roll says nothing about the odds being good: a case with a 30% house edge can be perfectly provably fair. Full walkthrough in our provably fair guide.
Every platform in our directory is tested with real deposits and withdrawals, and re-checked monthly.